Gas-filled incandescent lamp and getter therefor



Patented Sept. 21,1927.

UNITED STATES IIPIATENT OFFICE.

DANIEL SNYDER GUSTIN, OF NEWARK, NEW JERSEY, ASSIGNOR TO WESTINGHOUSELAMP COMPANY, A CORPORATION OF PENNSYLVANIA.

GAS-FILLED INCANDESCENT LAMP AND GETTER THEREFOR.

No Drawing.

This invention relates to incandescent electric lamps and moreparticularly to getters for such lamps.

An object of my invention is the production of a getter especiallyadapted for gasfilled incandescent lamps and of such a character thatthe exhaust operations thereof may be sim )lified.

Another ob ect of my invention is the preparation of a getter forapplication to the filaments in gas-filled incandescent lamps in theform of a solution.

A further object of my invention is the employment of certain organiccompounds as getters in gas-filled incandescent lamps,

whereby it is unnecessary to use a hot-exhaust, because of thesensitivity of such getters.

A still further object of my invention is the manufacture of gas-filledincandescent electric lamps, upon the filaments of which is getteredbenzidine, a solution thereof or its equivalent.

Other objects and advantages of the invention will become apparent uponreading the following description.

In the manufacture of incandescent electric lamps, it has beenconsidered practically essential to heat the bulbs thereof, While beingexhausted, to free them substantially from moisture and occluded gases.

IVhat is termed cold-exhaust that is, the omission to heat the bulbduring the exhausting operation, has been tried without obtaining thedesired results, when using previous forms of getters or materials forcleaning-up or rendering harmless certain impurities in the gaseousfilling of gas-filled incandescent lamps, for example, moisture,

4 oxygenand nitrogen. In the past it has also been customary, if notessential, to apply the getters used to the filamentary material in theform of a. suspension or as solids. This is more or less undesirablebecause it is difiicult to apply the getter by such a manner in auniform coating on the filament.

According to my invention, I have prepared a getter, or substance forimproving the operation of gas-filled incandescent lamps especially,which may be applied to the filament thereof in solid form or as asolution in either alcohol, water or other solvent and which is soactive for cleaning Application filed May 16,

up deleterious gases and vapors in such lamps that the heating of thebulbs thereof during exhaust may be dispensed with. Likewise, extremepurification of the gas used for filling the lamps is unnecessary,because the getter exerts a strong purifying action thereon. Briefly, mygetter in its preferred form, comprises a solution of benzidine or .dipara diamino diphenyl (N H,),( C l-I and preferably, but notnecessarily, in alcoholic solution, because it is more soluble inalcohol and if such a solution is used it will dry more readily afterapplication to the filament. Although the application directed to thefilament as a solution is preferred, I may find it desirable tointroduce it in the form of a vapor with the gaseous filling. i

My invention will better be understood by the following more detaileddescription thereof.

I preferably prepare my getter by dissolving benzidine in alcohol so asto make about a 2% solution thereof. The filamentary material, which ispreferably of the concentrated or coil type, after mounting in the usualmanner, may be dipped in the solution or if desired, may be dipped,sprayed or otherwise coated with the solution before mounting. Themounted filament may then be sealed into the. lamp bulb in the usualmanner, the lamp exhausted, either hot .or cold, as it has been foundthat good results are obtained by this method using a cold-exhaust,although if for any reason it is desired to retain the hot exhaust, thesame is not detrimental "when using my getter.

After exhaustion, the bulb is preferably flushed with nitrogen and ifdesired that the final gas filling be argon or other inert gas, thenitrogen may then be pumped out and replaced by a filling of argon, atthe desired pressure, after which, the lamp may be tipped off. Thefilament is flashed, preferably at a White heat or temperature slightlyabove normal operating temperature which is above that at which tungstencarbide decomposes, to avoid making the filament brittle.

On flashing the filament gettered with benzidine, it was found that,even though a cold exhaust was employed, lamps of very good exhaustingsuch lamps hot according to pre-' vious practice. When initiallyliflting or flashing lamps the filaments of which were gettered withbenzidine fumes were noticeable and it is though that the benzidine isdecomposed by such treatment, forming unsaturated compounds which have agreat aflinity for other substances, especially impurities on argon orother inert gas used for filling gas-filled lamps, although I do notwish to be restricted by any theory of operation of my getter.

' When using such a getter while employing a hot exhaust, it was foundthat no fuming occurred upon initial'flashing, probably indicating thatthe getter, or part of it, was

volatilized oil during the exhausting opera-' tion. The lainps were ofgood quality however, showing that it is not necessary that the getterbe actually on the filament to accomplish the desired result andindicating that it may be introduced with the gas filling, if desired.In fact, naphthalene, (2 11,, which is a compound similar to benzidine,has been used successfully in this manner. Argon was passed through a.tube containing naphthalene and then used for filling lamps.

Lamps gettered with benzidine .were bump-tested after seasoning andfound to be about normal for their type of lamp. Comparative tests showthat lamps with benzidinc getters were equal to or slightly better thanthwe made by the regular process, with respect to blackening of thebulb.

Although benzidine has been mentioned as the preferred material for agetter, accord ing to my invention, I do not wish to be restrlctedthereto as various other materials of the same character, for example,cyclic compounds, unsaturated carbon compounds and those which areeither" unsaturated or from which unsaturated compounds res t onheating, may he used. All such compounds preferably should containlittle or no oxygen or oxidizing material. Such materials includediphenyl and higher homologues thereof. together with amino compoundsand their deriva ives, isomers and homologues. A few specific examplesof such compounds are as follows: crystal violet C G QW JQ) 5, ip l 5 5)diphenyl-imide or carbazole {C HQ KH. or-

-tho-amino-diphenyl NHOC HflI- F acetylene C H anthracene (C H (CH)together with their isomers, homologues and derivatives.

Although I have described what is now considered a preferred emiiodimentof my invention, it is to be understcod that the same is merelyillustrative and that I wish to be restricted only by the spirit andscope of the appended claims,

oeasro What is claimed is:

1. An incandescent electric lamp of the gas-filled type containing anoxygen-free, organic getter.

2. An incandescent electric lamp of the gas-filled type containing anorganic compound, substantially free from oxidizing material, applied inthe form of a solution to the filament thereof.

3. An incandescent electric lamp of the gas-filled type to which hasbeen applied a solution of a carbon compound substantially fiee fromoxygen.

4. An incandescent electric lamp of the gas-filled type comprising afilament coated with a derivative 0 diphenyl.

5. An incandescent electric lamp of the gas-filled type containing afilament which as-applied thereto, a solution of an amino compound. 7 r

6. An incandescent electric lamp of the gas-filled type comprising afilament coated with a cyclic carbon compound free from oxygen.

11. An incandescent electric lamp of the gas-filled type comprising atungsten filament to which has been applied about a 2% solution orhenzidine.

12. A getter for g s-iilled incandescentv electric lamps comprising acyclic organic compound substantially free from oxygen.

13. A getter suitable for gas-filled incandescent electric lampscomprising a derivative of diphenyl.

14. A getter suitable for incandescent electric lamps of the gasfilledtype comprising an amino compound.

15. A getter suitable for gas-filled incandescent electric lampscomprising benzidine.

16. A getter suitable for incandescent electric lamps of the gas-filledtype comprising a solution of benzidine.

In testimony whereof I have hereunto subscribed my name this 15th day ofMay, 1923.

DANEL SNYDER GUSTIN.

